Explanation:
The ominous, dark shapes haunting the left side of the Sun are
coronal
holes -- low density regions extending above
the surface
where the solar magnetic field opens freely into
interplanetary space.
Studied extensively
from
space since the 1960s in ultraviolet
and x-ray light,
coronal holes are known to be the source of
the high-speed solar wind, atoms and electrons
which flow outward along the open
magnetic field lines.
During periods of low activity,
coronal holes typically cover
regions just above the Sun's poles.
These coronal holes, however, have just
moved into view near the Sun's equator,
and particles escaping them have already caused
notable aurora here on Earth.
Coronal holes
like this one may last for a few solar rotations
before the magnetic fields shift and change configurations.
Shown in false-colour, this picture of the Sun on March 9
was made in extreme ultraviolet light by the
EIT
instrument on board the space-based SOHO observatory.